1.1 什么是Curl?

Curl 是一个命令行工具和库，用于通过URL传输数据。

简单来说呢，根据我的理解

Curl 就是一个可以通过命令行发送GET,POST 等多种协议请求的工具。

1.2 Curl 支持的网络协议

DICT, FILE, FTP, FTPS, Gopher, HTTP, HTTPS, IMAP, IMAPS, LDAP, LDAPS,
POP3, POP3S, RTMP, RTSP, SCP, SFTP, SMB, SMBS, SMTP, SMTPS, Telnet and
TFTP. curl supports SSL certificates, HTTP POST, HTTP PUT, FTP
uploading, HTTP form based upload, proxies, HTTP/2, cookies,
user+password authentication (Basic, Plain, Digest, CRAM-MD5, NTLM,
Negotiate and Kerberos), file transfer resume, proxy tunneling and
more.

1.3 Curl 是做什么用的？

• Curl在命令行或脚本中用于传输数据。
• 它还用于汽车，电视机，路由器，打印机，音频设备，手机，平板电脑，机顶盒，媒体播放器中，并且是数千种每天影响数十亿人口的软件应用程序的互联网传输基础。
• Curl 是免费开源的

1.4 Curl 如何下载安装？

1.4.1 Windows 平台

2019年9月11日 当前最新版本是7.66.0

Curl 点击下载

打开上面网址后，我们可以看到这样的界面

• 如果是windows 操作系统就点击图中所示这个。
• 如果是linux 请下载对应的版本。

1.4.2 Linux 平台

Linux 平台的下载和安装方法见这里 Get curl for Linux

1.4.3 Mac OS 平台

如果你使用的Mac OS 操作系统，那么可以参考Get curl for macOS

1.5 Curl 配置

1.5.1 解压

下载完成后，我解压到了这样一个目录

C:\app\curl\curl-7.66.0

1.5.2 配置环境变量

Curl 和其他一些常用的Java 工具一样，如果我们想要在命令行的任意路径下使用它，最好把它添加到Path环境变量里。

我们新建一个环境变量

CURL_HOME
C:\app\curl\curl-7.66.0

效果如图所示

然后Path中追加这个环境变量即可

%CURL_HOME%\bin\

效果图如下所示

1.5.3 验证安装配置是否成功

如果想验证是否安装配置成功，可以输入如下命令即可

curl --version

或者

curl -v / --version

值得注意的是，貌似它针对windows 平台的Powshell 支持不够友好，输入这个名会报错，只能在cmd下才可以。

1.6 如何使用Curl?

官方文档
GitHub 主页

命令行下输入命令

curl --help

输出命令语法如下：

Usage: curl [options...] <url>--abstract-unix-socket <path> Connect via abstract Unix domain socket--anyauth       Pick any authentication method-a, --append        Append to target file when uploading--basic         Use HTTP Basic Authentication--cacert <CA certificate> CA certificate to verify peer against--capath <dir>  CA directory to verify peer against-E, --cert <certificate[:password]> Client certificate file and password--cert-status   Verify the status of the server certificate--cert-type <type> Certificate file type (DER/PEM/ENG)--ciphers <list of ciphers> SSL ciphers to use--compressed    Request compressed response-K, --config <file> Read config from a file--connect-timeout <seconds> Maximum time allowed for connection--connect-to <HOST1:PORT1:HOST2:PORT2> Connect to host-C, --continue-at <offset> Resumed transfer offset-b, --cookie <data> Send cookies from string/file-c, --cookie-jar <filename> Write cookies to <filename> after operation--create-dirs   Create necessary local directory hierarchy--crlf          Convert LF to CRLF in upload--crlfile <file> Get a CRL list in PEM format from the given file-d, --data <data>   HTTP POST data--data-ascii <data> HTTP POST ASCII data--data-binary <data> HTTP POST binary data--data-raw <data> HTTP POST data, '@' allowed--data-urlencode <data> HTTP POST data url encoded--delegation <LEVEL> GSS-API delegation permission--digest        Use HTTP Digest Authentication-q, --disable       Disable .curlrc--disable-eprt  Inhibit using EPRT or LPRT--disable-epsv  Inhibit using EPSV--dns-interface <interface> Interface to use for DNS requests--dns-ipv4-addr <address> IPv4 address to use for DNS requests--dns-ipv6-addr <address> IPv6 address to use for DNS requests--dns-servers <addresses> DNS server addrs to use-D, --dump-header <filename> Write the received headers to <filename>--egd-file <file> EGD socket path for random data--engine <name> Crypto engine to use--expect100-timeout <seconds> How long to wait for 100-continue-f, --fail          Fail silently (no output at all) on HTTP errors--fail-early    Fail on first transfer error, do not continue--false-start   Enable TLS False Start-F, --form <name=content> Specify HTTP multipart POST data--form-string <name=string> Specify HTTP multipart POST data--ftp-account <data> Account data string--ftp-alternative-to-user <command> String to replace USER [name]--ftp-create-dirs Create the remote dirs if not present--ftp-method <method> Control CWD usage--ftp-pasv      Use PASV/EPSV instead of PORT-P, --ftp-port <address> Use PORT instead of PASV--ftp-pret      Send PRET before PASV--ftp-skip-pasv-ip Skip the IP address for PASV--ftp-ssl-ccc   Send CCC after authenticating--ftp-ssl-ccc-mode <active/passive> Set CCC mode--ftp-ssl-control Require SSL/TLS for FTP login, clear for transfer-G, --get           Put the post data in the URL and use GET-g, --globoff       Disable URL sequences and ranges using {} and []-I, --head          Show document info only-H, --header <header/@file> Pass custom header(s) to server-h, --help          This help text--hostpubmd5 <md5> Acceptable MD5 hash of the host public key-0, --http1.0       Use HTTP 1.0--http1.1       Use HTTP 1.1--http2         Use HTTP 2--http2-prior-knowledge Use HTTP 2 without HTTP/1.1 Upgrade--ignore-content-length Ignore the size of the remote resource-i, --include       Include protocol response headers in the output-k, --insecure      Allow insecure server connections when using SSL--interface <name> Use network INTERFACE (or address)-4, --ipv4          Resolve names to IPv4 addresses-6, --ipv6          Resolve names to IPv6 addresses-j, --junk-session-cookies Ignore session cookies read from file--keepalive-time <seconds> Interval time for keepalive probes--key <key>     Private key file name--key-type <type> Private key file type (DER/PEM/ENG)--krb <level>   Enable Kerberos with security <level>--libcurl <file> Dump libcurl equivalent code of this command line--limit-rate <speed> Limit transfer speed to RATE-l, --list-only     List only mode--local-port <num/range> Force use of RANGE for local port numbers-L, --location      Follow redirects--location-trusted Like --location, and send auth to other hosts--login-options <options> Server login options--mail-auth <address> Originator address of the original email--mail-from <address> Mail from this address--mail-rcpt <address> Mail from this address-M, --manual        Display the full manual--max-filesize <bytes> Maximum file size to download--max-redirs <num> Maximum number of redirects allowed-m, --max-time <time> Maximum time allowed for the transfer--metalink      Process given URLs as metalink XML file--negotiate     Use HTTP Negotiate (SPNEGO) authentication-n, --netrc         Must read .netrc for user name and password--netrc-file <filename> Specify FILE for netrc--netrc-optional Use either .netrc or URL-:, --next          Make next URL use its separate set of options--no-alpn       Disable the ALPN TLS extension-N, --no-buffer     Disable buffering of the output stream--no-keepalive  Disable TCP keepalive on the connection--no-npn        Disable the NPN TLS extension--no-sessionid  Disable SSL session-ID reusing--noproxy <no-proxy-list> List of hosts which do not use proxy--ntlm          Use HTTP NTLM authentication--ntlm-wb       Use HTTP NTLM authentication with winbind--oauth2-bearer <token> OAuth 2 Bearer Token-o, --output <file> Write to file instead of stdout--pass <phrase> Pass phrase for the private key--path-as-is    Do not squash .. sequences in URL path--pinnedpubkey <hashes> FILE/HASHES Public key to verify peer against--post301       Do not switch to GET after following a 301--post302       Do not switch to GET after following a 302--post303       Do not switch to GET after following a 303--preproxy [protocol://]host[:port] Use this proxy first-#, --progress-bar  Display transfer progress as a bar--proto <protocols> Enable/disable PROTOCOLS--proto-default <protocol> Use PROTOCOL for any URL missing a scheme--proto-redir <protocols> Enable/disable PROTOCOLS on redirect-x, --proxy [protocol://]host[:port] Use this proxy--proxy-anyauth Pick any proxy authentication method--proxy-basic   Use Basic authentication on the proxy--proxy-cacert <file> CA certificate to verify peer against for proxy--proxy-capath <dir> CA directory to verify peer against for proxy--proxy-cert <cert[:passwd]> Set client certificate for proxy--proxy-cert-type <type> Client certificate type for HTTS proxy--proxy-ciphers <list> SSL ciphers to use for proxy--proxy-crlfile <file> Set a CRL list for proxy--proxy-digest  Use Digest authentication on the proxy--proxy-header <header/@file> Pass custom header(s) to proxy--proxy-insecure Do HTTPS proxy connections without verifying the proxy--proxy-key <key> Private key for HTTPS proxy--proxy-key-type <type> Private key file type for proxy--proxy-negotiate Use HTTP Negotiate (SPNEGO) authentication on the proxy--proxy-ntlm    Use NTLM authentication on the proxy--proxy-pass <phrase> Pass phrase for the private key for HTTPS proxy--proxy-service-name <name> SPNEGO proxy service name--proxy-ssl-allow-beast Allow security flaw for interop for HTTPS proxy--proxy-tlsauthtype <type> TLS authentication type for HTTPS proxy--proxy-tlspassword <string> TLS password for HTTPS proxy--proxy-tlsuser <name> TLS username for HTTPS proxy--proxy-tlsv1   Use TLSv1 for HTTPS proxy-U, --proxy-user <user:password> Proxy user and password--proxy1.0 <host[:port]> Use HTTP/1.0 proxy on given port-p, --proxytunnel   Operate through a HTTP proxy tunnel (using CONNECT)--pubkey <key>  SSH Public key file name-Q, --quote         Send command(s) to server before transfer--random-file <file> File for reading random data from-r, --range <range> Retrieve only the bytes within RANGE--raw           Do HTTP "raw"; no transfer decoding-e, --referer <URL> Referrer URL-J, --remote-header-name Use the header-provided filename-O, --remote-name   Write output to a file named as the remote file--remote-name-all Use the remote file name for all URLs-R, --remote-time   Set the remote file's time on the local output-X, --request <command> Specify request command to use--request-target Specify the target for this request--resolve <host:port:address> Resolve the host+port to this address--retry <num>   Retry request if transient problems occur--retry-connrefused Retry on connection refused (use with --retry)--retry-delay <seconds> Wait time between retries--retry-max-time <seconds> Retry only within this period--sasl-ir       Enable initial response in SASL authentication--service-name <name> SPNEGO service name-S, --show-error    Show error even when -s is used-s, --silent        Silent mode--socks4 <host[:port]> SOCKS4 proxy on given host + port--socks4a <host[:port]> SOCKS4a proxy on given host + port--socks5 <host[:port]> SOCKS5 proxy on given host + port--socks5-basic  Enable username/password auth for SOCKS5 proxies--socks5-gssapi Enable GSS-API auth for SOCKS5 proxies--socks5-gssapi-nec Compatibility with NEC SOCKS5 server--socks5-gssapi-service <name> SOCKS5 proxy service name for GSS-API--socks5-hostname <host[:port]> SOCKS5 proxy, pass host name to proxy-Y, --speed-limit <speed> Stop transfers slower than this-y, --speed-time <seconds> Trigger 'speed-limit' abort after this time--ssl           Try SSL/TLS--ssl-allow-beast Allow security flaw to improve interop--ssl-no-revoke Disable cert revocation checks (WinSSL)--ssl-reqd      Require SSL/TLS-2, --sslv2         Use SSLv2-3, --sslv3         Use SSLv3--stderr        Where to redirect stderr--suppress-connect-headers Suppress proxy CONNECT response headers--tcp-fastopen  Use TCP Fast Open--tcp-nodelay   Use the TCP_NODELAY option-t, --telnet-option <opt=val> Set telnet option--tftp-blksize <value> Set TFTP BLKSIZE option--tftp-no-options Do not send any TFTP options-z, --time-cond <time> Transfer based on a time condition--tls-max <VERSION> Use TLSv1.0 or greater--tlsauthtype <type> TLS authentication type--tlspassword   TLS password--tlsuser <name> TLS user name-1, --tlsv1         Use TLSv1.0 or greater--tlsv1.0       Use TLSv1.0--tlsv1.1       Use TLSv1.1--tlsv1.2       Use TLSv1.2--tlsv1.3       Use TLSv1.3--tr-encoding   Request compressed transfer encoding--trace <file>  Write a debug trace to FILE--trace-ascii <file> Like --trace, but without hex output--trace-time    Add time stamps to trace/verbose output--unix-socket <path> Connect through this Unix domain socket-T, --upload-file <file> Transfer local FILE to destination--url <url>     URL to work with-B, --use-ascii     Use ASCII/text transfer-u, --user <user:password> Server user and password-A, --user-agent <name> Send User-Agent <name> to server-v, --verbose       Make the operation more talkative-V, --version       Show version number and quit-w, --write-out <format> Use output FORMAT after completion--xattr         Store metadata in extended file attributes

关于Curl 如何使用HTTP ,官方有个文档

在HTTP 请求中，最常用的是下面几个方法：

• GET
• POST
• HEAD
• PUT

其中，Curl 方法执行约定如下

• 默认使用的是GET方法。
• -d 或者-F 指定为POST 方法
• -I 指定为HEAD方法
• -T 指定为PUT 方法

示例

1.6.1 发送一个GET 请求

curl http://example.com/file

执行完成后我们可以看到请求后返回来相应的页面源码

1.6.2 发送一个POST 请求

示例一:

curl -d 'name=admin&shoesize=12' http://example.com/

示例二：

curl -d name=admin -d shoesize=12 http://example.com/

示例三：

curl -d @filename http://example.com

1.6.3 发送一个DELETE

刚才默认的请求是GET 请求，我们也可以通过-X 参数指定请求的方法为DELETE

curl http://example.com/file -X DELETE

1.6.4 自定义请求头

如果自定义请求头，可以这么做

curl -H "Elevator: floor-9" http://example.com/

输出内容如下：

要修改User-Agent,那么输入如下命令：

curl -H "User-Agent:" http://example.com/

输出内容如下：

1.6.5 发送一个PUT 请求

发送一个PUT 请求使用-T 参数，命令如下：

curl -T localfile http://example.com/new/resource/file

因此-T表示PUT并告诉curl发送哪个文件，locafile 必须指定一个本地文件路径

但是POST和PUT之间的相似之处还允许您通过使用-d的常规curl POST机制来发送带有字符串的PUT，但要求它改为使用PUT：

curl -d "data to PUT" -X PUT http://example.com/new/resource/file

1.7 附录

关于参数列表如下：

Verbose	Hide progress	extra info	Write output	Timeout
-v	-s	-w “format”	-O	-m
–trace-ascii			-o
POST	multipart	PUT	HEAD	custom
-d “string”	-F name=value	-T	-I	-X “METHOD”
-d @file	-F name=@file
Basic auth	read cookies	write cookies	send cookies	user-agent
-u user:password	-b	-c	-b “c=1; d=2”	-A “string”
Use proxy	Headers, add/remove	follow redirs	gzip	insecure
-x	-H “name: value”	-L	–compressed	-k
	-H “name:”

1.8 更多学习资料

• How to read this book
• CURL With HTTP
• HTTP POST